Posted!

Join the Conversation

Comments

Welcome to our new and improved comments, which are for subscribers only.
This is a test to see whether we can improve the experience for you.
You do not need a Facebook profile to participate.

You will need to register before adding a comment.
Typed comments will be lost if you are not logged in.

Please be polite.
It's OK to disagree with someone's ideas, but personal attacks, insults, threats, hate speech, advocating violence and other violations can result in a ban.
If you see comments in violation of our community guidelines, please report them.

Oroville Dam crisis in Northern California: What we know

In this Saturday, Feb. 11, 2017, water flows down Oroville Dam's main spillway near Oroville, Calif. Officials ordered residents near the Oroville Dam to evacuate the area Sunday, Feb. 12, saying a "hazardous situation is developing" after an emergency spillway severely eroded.(Photo: Rich Pedroncelli, AP)

The tallest dam in the United States has a large section crumbling of its main spillway. Thousands of people who live downstream of the Oroville Dam were ordered to evacuate on Sunday. By Tuesday afternoon, residents were told they could return to their homes while officials still work to fix the damaged spillway.

Portions of the 143-mile Herbert Hoover Dike in Florida are 80 years old and eroding. A business leader hopes the Oroville crisis brings into greater focus a years-long effort to shore up the eroding dike.

"There is no anticipated threat to the dam or the public," said California Department of Water Resources officials said in a press release that day. Six days later, the lake overflowed and an emergency spillway began to fail.

Rainy weather expected throughout the week is further exasperating state officials who are working around the clock to prevent massive flooding.

Wednesday updates:

Butte County Sheriff Kory Honea lifted mandatory evacuations for Oroville and other areas of the county midday Wednesday, allowing thousands to return to their homes. Still, those residents are preparing to possibly leave again later this week. Read more.

Tuesday updates:

President Donald Trump declared a federal disaster late Tuesday for areas affected by a potential collapse in a spillway that holds back Lake Oroville, California’s second-largest reservoir, even as authorities told 188,000 evacuated downstream residents they could go home.

The president’s order covers Butte, Sutter and Yuba counties, according to the Federal Emergency Management Agency. It authorizes FEMA to coordinate relief efforts and opens up federal emergency aid to state, tribal and local agencies. Read more.

There have been 290 reports of damage to highways up and down the Golden State, and they're expected to cost at least $401 million, Caltrans spokesman Mark Dinger said.

Dinger didn't have previous years' damage totals but said it was likely this year's price tag would exceed those.

Among the most expensive damage was Highway 37 flooding in Marin County, which cost $11.5 million, and a collapse that caused $10.4 million in damage to Highway 1 near Muir Beach, also in Marin County. Read more.

Water from Lake Oroville poured over the spillway Sunday and caused damage so extensive the Butte County Sheriff ordered the evacuation of nearly 200,000 downstream residents.

As soon as the water stopped, efforts to repair the damage began. Still, even if workers manage to cover the exposed, earthen slope dam safety experts say there's no guarantee the makeshift fix would survive a real world test.

“Hope is part of the strategy there,” said Jeffrey Mount, a founding director at the Center for Watershed Sciences at University of California, Davis. Read more.

The evacuation order has been changed to a warning, the Butte County sheriff said at a news conference this afternoon in Oroville.

The change means residents can return to their home but must stay alert in case the situation changes, Sheriff Kory Honea said.

"This reduction to an evacuation warning properly balances people to assume their lives, but allows them to deal with increased threat," he said. "The (California Department of Water Resources) and Butte County sheriff will continue to monitor the situation."

As the news of the evacuation order being changed to a warning spread through the Silver Dollar Fairgrounds in Chico, people immediately started leaving. Read more.

1. The evacuation order is still in place. Officials say residents who live in the evacuation area should stay away. Those who have remained in the area should try to stay in a safe place, on higher ground and be ready to leave quickly, said Chris Orrock, public information officer for the California Department of Water Resources.

2. Erosion has stopped on the emergency spillway, Orrock said. The dam itself has not been affected, only the main spillway and the emergency spillway suffered erosion. No more water is coming off the emergency spillway, but releases from the main spillway continue at 100,000 cubic feet per second as dam operators scramble to draw the water level to 50 feet below the top of the dam, or about 850 feet deep. As of this morning, it was about 11 feet from crest. Read more.

After high water levels put California's Oroville Dam in peril and prompted the evacuation of about 200,000 people this weekend, Northern Colorado residents might be wondering about the safety of nearby dams.

The good news: All of Larimer County's biggest dams, including the dams at Horsetooth Reservoir, have emergency action plans designed to prepare authorities for emergencies like what happened in California this weekend.

And the bad: A small percentage of Colorado's higher-hazard dams don't have emergency plans. Failure could put human lives, environment and property at risk. Read more.

As Northern California fights to keep a massive wall of water from breaching Oroville Dam, a business leader in Clewiston hopes the California crisis brings into greater focus a years-long effort to shore up the eroding dike protecting communities near Florida’s Lake Okeechobee.

“My biggest concern is the integrity of the (Herbert Hoover) Dike,” said Hillary Hyslope, executive director of the Clewiston Chamber of Commerce.

Hyslope said she's been following news coverage of the evacuations and other emergency response measures in Oroville closely.

Portions of the 143-mile Herbert Hoover Dike are 80 years old and eroding. Read more.

As more than 180,000 residents living near the Oroville Dam evacuated on Sunday and Monday, the USA TODAY NETWORK analyzed dam inspections in California. The results are stark: As of January 2016, 710 dams out of the 1,585 dams in California, nearly 44 percent, had not been inspected within their scheduled inspection frequency. In Sonoma County, 82 percent of the 65 dams haven’t been inspected on schedule. In San Bernardino County, that number was 83 percent of 40 dams. Take a look.

It was just before midnight March 12, 1928, when the St. Francis Dam north of Santa Clarita collapsed, sending 12 billion gallons of water gushing to the Pacific Ocean and killing at least 530 people.

The torrent raced 54 miles down the Santa Clara River Valley, a 180-foot wall of water sweeping away homes, livestock, vegetation and people. It was California’s second-worst disaster at the time after the San Francisco earthquake and fire.

The tragedy is considered one of the worst American civil engineering failures of the 20th century and ended the career of William Mulholland, the legendary, self-taught engineer who built the Owens River Aqueduct and made it possible for modern Los Angeles to flourish. Read more.

The federal government has ordered California to immediately design repairs to the Oroville Dam's damaged primary and emergency spillways.

In a letter dated Feb. 13, the Federal Energy Regulatory Commission ordered the California Department of Water Resources to "initiate immediate design of emergency repair to minimize further degradation" of both structures, which have been eroding as water flows out of Lake Oroville this week. Read more.

Monday updates:

The area surrounding the Oroville Dam crisis is on track to have its wettest year on record, further exasperating state officials who are working around the clock to prevent massive flooding. Read more.

"There is no anticipated threat to the dam or the public," DWR officials said in a press release that day. Six days later, the lake overflowed and an emergency spillway began to fail. Here's what happened since Tuesday, based on what we know so far. Read more.

In 2005, three environmental groups raised concerns that the emergency spillway at California’s Oroville Dam wasn’t properly built and posed serious risks.

The groups – Friends of the River, Sierra Club and the South Yuba River Citizen’s League – described their worries in a motion to the Federal Energy Regulatory Commission, which was considering the dam’s relicensing.

The environmentalists wanted federal officials to require modifications including building a concrete-armored spillway rather than leaving it a concrete “lip” above an unprotected hillside prone to erosion damage. Read more.

As the nation's 84,000 dams continue to age, a growing number of people downstream of these structures are at risk, according to experts and data of the nation's dams.

It's a problem highlighted by Oroville Dam, which suffered a potential failure of its emergency spillway.

The USA TODAY NETWORK reviewed the latest data in the National Inventory of Dams, which is compiled by the Army Corps of Engineers and shows 15,498 dams across the United States are characterized as high hazard, meaning the loss of at least one human life is likely if the dam were to fail. Read the full report.

The potential failure of California's Oroville spillway — which caused nearly 200,000 people to flee their homes late Sunday — is further proof that the punishing five-year drought in the northern part of the state is over.

Oroville Dam holds back swollen Lake Oroville, which is the state's second-largest reservoir and at 100% capacity because of recent heavy rain and snow. Read more.

A pair of storms is expected to hit the state this week, and forecasters say they will be strong enough to bring 2 to 6 inches of rain to Oroville.

Forecasters anticipate a moderate storm Wednesday with a “really big and strong” storm Friday, said Brandt Maxwell, National Weather Service meteorologist. Another 8 inches of rain could fall in the mountains before draining into Lake Oroville, and that would increase the flow of water at the dam where severe erosion could drop the top of the spillway enough for water to pour out uncontrolled. Read more.

Lake Oroville has dropped about 3.5 feet overnight after officials doubled the flows down the Feather River on Sunday, and an additional 1.5 feet Monday morning.

Still, downstream communities facing the threat of uncontrolled flooding remain evacuated from their homes with no word on when they'll be allowed to return.

Crews transported truckloads of rocks to a staging area near Oroville Dam's failing emergency spillway Monday morning as emergency officials briefed local lawmakers on the situation.

As of 5 a.m., evacuations in Butte County remain in place and Highways 70 and 99 are closed starting about 7 miles south of Chico. The Salvation Army Chico Corps will begin providing food Monday to those who went to the Silver Dollar Fairgrounds in Chico. Read more.

State officials' efforts to deal with the Oroville Dam crisis could determine not only whether entire towns are inundated but also whether the state’s second-largest reservoir emerges with manageable damage or something much worse.

“It would be a massive blow to the state’s water system if they lose Oroville,” said Peter Gleick, a water researcher at the Oakland-based Pacific Institute. “The question is, will it erode away the emergency spillway? Will there be a big uncontrolled release of water? Or will they be able to draw the lake down enough to prevent that?”

He said the big worry is not that the dam itself would fail, but that a failure of the spillway could cut into the hillside and potentially release more and more water, leading to a “cascading failure.” Read more.

Posted!

A link has been posted to your Facebook feed.

In this Saturday, Feb. 11, 2017, water flows down Oroville Dam's main spillway near Oroville, Calif. Officials ordered residents near the Oroville Dam to evacuate the area Sunday, Feb. 12, saying a "hazardous situation is developing" after an emergency spillway severely eroded. Rich Pedroncelli, AP

Kendra Curieo waits in traffic to evacuate Marysville, Calif., Sunday, Feb. 12, 2017. Thousands of residents of Marysville and other Northern California communities were told to leave their homes Sunday evening as an emergency spillway of the Oroville Dam could fail at any time unleashing flood waters from Lake Oroville, according to officials from the California Department of Water Resources. Rich Pedroncelli, AP

California Highway Patrol officer Ken Weckman directs traffic as residents evacuate Marysville, Calif., Sunday, Feb. 12, 2017. Thousands of residents of Marysville and other Northern California communities were told to leave their homes Sunday evening as an emergency spillway of the Oroville Dam could fail at any time unleashing flood waters from Lake Oroville, according to officials from the California Department of Water Resources. Paul Kitagaki Jr., AP

A driver waits in traffic to evacuate Marysville, Calif., Sunday, Feb. 12, 2017. Thousands of residents of Marysville and other Northern California communities were told to leave their homes Sunday evening as an emergency spillway of the Oroville Dam could fail at any time unleashing flood waters from Lake Oroville, according to officials from the California Department of Water Resources. Rich Pedroncelli, AP

In this Feb. 11, 2017, photo released by the California Department of Water Resources, water flows over an emergency spillway at the Oroville Dam at Lake Oroville in Oroville, Calif. Water will continue to flow over the emergency spillway at the nation's tallest dam for another day or so, officials said Sunday. Albert Madrid, AP

This Feb. 11, 2017, photo released by the California Department of Water Resources shows the main spillway, bottom, and an auxiliary spillway, upper, of the Oroville Dam at Lake Oroville in Oroville, Calif. Water will continue to flow over the emergency spillway at the nation's tallest dam for another day or so, officials said Sunday. William Croyle, AP

This Friday, Feb. 10, 2017 image from video provided by the office of Assemblyman Brian Dahle shows water flowing over an emergency spillway of the Oroville Dam in Oroville, Calif., during a helicopter tour by the Butte County Sheriff's office. About 150 miles northeast of San Francisco, Lake Oroville is one of California’s largest man-made lakes, and the 770-foot-tall Oroville Dam is the nation's tallest. Josh F.W. Cook, AP

Muddy water rushes down the emergency spillway at Oroville Dam, Saturday, Feb. 11, 2017, in Oroville, Calif. Water started flowing over the emergency spillway at the nation's tallest dam for the first time Saturday after erosion damaged the Northern California dam's main spillway. Rich Pedroncelli, AP

Jason Newton, of the Department of Water Resources, takes a picture of water going over the emergency spillway at Oroville Dam Saturday, Feb. 11, 2017, in Oroville, Calif. Water started flowing over the emergency spillway, at the nation's tallest dam, for the first time Saturday morning after erosion damaged the Northern California dam's main spillway. Rich Pedroncelli, AP

Jason Newton, of the Department of Water Resources, takes a picture of water going over the emergency spillway at Oroville Dam Saturday, Feb. 11, 2017, in Oroville, Calif. Water started flowing over the emergency spillway at the nation's tallest dam for the first time Saturday after erosion damaged the Northern California dam's main spillway. Rich Pedroncelli, AP

Muddy water rushes down the emergency spillway at Oroville Dam, Saturday, Feb. 11, 2017, in Oroville, Calif. Water started flowing over the emergency spillway at the nation's tallest dam for the first time Saturday after erosion damaged the Northern California dam's main spillway. Rich Pedroncelli, AP

A employee of the Department of Water Resources watches as water flows over the emergency spillway at Oroville Dam Saturday, Feb. 11, 2017, in Oroville, Calif. Water started flowing over the spillway, at the nation's tallest dam, for the first time Saturday morning after erosion damaged the Northern California dam's main spillway. Rich Pedroncelli, AP

Jason Newton, left, of the Department of Water Resources, takes a picture of water going over the emergency spillway at Oroville Dam Saturday, Feb. 11, 2017, in Oroville, Calif. Water started flowing over the spillway,at the nation's tallest dam, for the first time Saturday morning after erosion damaged the Northern California dam's main spillway. Rich Pedroncelli, AP

E. Knight uses his smartphone to record muddy water rushing down the emergency spillway at Oroville Dam, Saturday, Feb. 11, 2017, in Oroville, Calif. Water started flowing over the emergency spillway at the nation's tallest dam for the first time Saturday after erosion damaged the Northern California dam's main spillway. Rich Pedroncelli, AP